CUTTING MACHINES

SUBMITTED BY PROTIM SAIKIA AAMTS

Cutting
Fabric cutting is the most important part of garment industry. Cutting different parts of garment apparel very carefully according to shape of pattern is called fabric cutting. Consistent fabric cutting is very important for perfect garments making.

Requirement of cutting
Precision of cut- To ensure the cutting of fabric aquirtly according to the line drown of the marker plan. Clean edge- By avoiding the fraing out of yarn from the fabric edge. Cutting edge must be smooth clean. Knife must be sharp for smooth or clean edge. Consistency in cutting- All the sizing safe of the cutting parts should be same of knife should be operated of the right angle of the fabric lay.

Hand operated scissor
Hand shears are normally used when cutting only single or double plies. The lower blade of the shears passes under the plies, but the subsequent distortion of the fabric is only temporary and accurate cutting to the line can be achieved with practice.

Advantage of hand scissor
Almost every type of cloth are cut by scissor. Scissors are mainly used for cutting single ply fabric.

Disadvantage of hand scissor
It takes huge time for fabric cutting It is impossible to cut the fabric lay of any height

Machine parts and their functions: a) Blade: Cuts the fabric laterally into a spread. b) Sharpening device: Produces degree of keenness in the cutting edge. c) Blade drive: Cutting blade is reciprocated vertically in the blade housing by the blade drive. It is driven by the motors drive. d) Blade housing : It is anchored in the base plate. It supports the motor, operating handle and sharpeners e) Blade guard: It is a safety device attached indirectly to the blade housing.

It has two functions-

safety and cutting quality.

It prevents the cutter from accidentally cutting his positioning hand on top of the spread.

f) Base plate: The foundation that supports and helps balance the cutting mechanism. It guides the knife in relation to the table surface and elevates the spread off thecutting table for contact with the blade. g) Handle: It moves the cutting machine or the cutter over the lines or area to be cut. h) Power system: It provides power to the drives for the motor drive to move blade drive whichdrives the blade.

Advantage of straight knife
The knife is comparatively cheap & can be transferred from one place to another easily. Lay of higher height can be cut very easily. Suitable for large production rate as it is convenient to cut the lay of 10 inches height. Fabric can be cut from any angle.

Disadvantage of straight knife
Sometimes deflecting may occur due to the weight of the motor. Chance of accident is high.
Blade deflection occurs so quality may be hampered. Skill hand required.

Servo assisted straight knife
The more recent development has been a travelling suspention system equipped with a modified straight knife. These system supports the knife from above, which allows the heavy base plate and rollers to be replaced with a small, flat plate, reducing the possibility of distortion during cutting which can arise from the thickness of the conventional base plate. Suspention from above also reduces the need for a heavy gauge standard behind the knife, and the width of the blade also reduces, allowing easier cutting of sharper curves. The drive trolley of the support arm moves automatically along rails on the side of the table supports as the straight knife is moved during the cutting process, allowing the best support to the knife at any part of the lay. These servo knife system enable a much higher degree of cutting accuracy than unsupported straight knife, with less operated unskill required. In many cases they allow a standard of cutting to be achieved with a straight cut that is normally only achievable by transporting roughly cut work to a band knife.

Round knife
Round knife is mostly use for cutting the big parts of the garments pattern. Advantage of round knife Round knife is widely used to separate the big parts and separate the blocks of fabric from relatively small height fabric lay.

Disadvantage of round knife
Not suitable for cutting very curved lines in higher number of lays as the blade does not strike all the piles simultaneously at the same point. Round knife is used only for straight line & lower number of piles. Not suitable for higher production. Possibility of accident is high. Difficult to cut small components.

Band knife
Band knife cutting machine is look like a wood cuttermachine. Band knife is used for precession cutting small parts of garment. This band knife cutting machine has lower noise, less temperature up, high power, less vibration and auto sharpening device. Cutting Blade 5" / 6" use narrow blade. 8" / 10" use wide blade.

Features of Band Knife Machine 1. 2. 3. 4. 5. 6. This machine worked as saw mill technique. Not possible to cut fabric directly from lay. Block pieces of fabric required in bundle form to cut by this machine. Blade moving vertically through a flat working table. Machine remains stationary and fabric is moveable. Specially used to cut small parts more accurately.

USES AND FEATURES Band knife cutting machine is a primary device equipment in garment and knitting etc industries. It could accurately cut the pattern of fabrics. This machine is with special blower decreases resistance between fabrics and table, which enables the fabrics be moved easily and be cut precisely. And it could adjustable speed to fit different fabrics.

Die cutting
Die cutting involves pressing a rigid blade through the lay of fabric. The die is a knife in the shape of a pattern periphery, including notches. One or more tie bars secure its stability. Free standing dies generally fall into two categories. They can be of strip steel, manufactured by bending the strip to the shape required and welding the joint. These cannot be sharpened and must be replaced when worn. Alternatively, they can be heavier gauge,forged dies which can be resharpened but which are about five times the price of strip steel. The position of the tie bars determines the depth of cut, which is generally greater with forged dies. Free standing dies cut the small parts of larger garments such as collars and trouser pocketing or the parts of smaller garments such as bras. They can also be used for part of a larger garment part., such as the neck area of a coat front. They provide a high standard of accuracy of cutting but, because of the cost of the dies, they are only appropriate to situations where large quantities of the same pattern shape will be cut.

Advantage of die cutting Die cutting is suitable for precession cutting of small parts of a garment. It is suitable for cutting the fabric in any angle & any shape. Especially suitable for knitted fabric.

Drill and Thread markers
Where reference marks are needed away from the edge of a garment part, such as for the position of pockets, darts and similar features, a hole is often drill through all the plies of fabric in the lay. The drill mounting includes a motor, a base plate with a hole to allow the drill to pass through, and a spirit level to ensure that the base is horizontal and hence the drill vertical. On looser weave fabrics, where the hole may close up, a hot drill is used, which will slightly scorch or fuse the edge of the hole. If It is important that no mark remains on the fabric , a long thread may be passed through the lay which is then cut with scissors between each ply, leaving a few centimeters visible on each garment panel. All drill holes must eventually be concealed by the construction of the garment. Advantage of drill It has heating arrangement. It has a system of yarn penetrating. Disadvantage of drill Burnt spot can come. The fabric become penetrated. Not suitable for loosely woven fabric

Notcher
The Hot Notcher is a multi-purpose tool used for marking and temporarily fusing loosely woven fabrics which can ensure precise alignment for sewing accuracy. The spread is held securely together and can be moved to the cutting area without shifting. The Hot Notcher marks a visible notch on materials instead of a slit notch which is not easily visible.

Many garment parts required that notches are cut into the edges of them to enable allignment during sewing with other garment parts. The accuracy depends on the operator specialised notching equipment provides greater straight notches are available. A further machine, the hot notcher , incorporates a heating element in order that the blade may slightly scorch the fibres adjacent to the notch in order to prevent it fraying and disappearing. This cannot be used in thermoplastic fibres or certain unlined garments. One fabric requiring it may be a loosely woven tweed. It is ideal for placing notches in a lay and has a depth adjustment guide to stop you notching too deeply. For example when you spread synthetic fabrics the Hot Notcher is used along the lay edge, at intervals, to seal the plies together which reduces movement and distortion. It has a depth capacity of 200mm and selectable temperatures of 300, 400 or 500oC. The Hot Notcher marks a visible notch on materials instead of a cutting machine slit which is hard to see.

Computer controlled knife cutting
This methods provides the most accurate possible cutting , at high speed, a typical computer system has a table with a cutting surface consisting of nylon bristles which support the fabric lays but are flexible enough to permit penetration and movement of the knife blade which is supported only on the top. The bristles also allow the passage of air through the table to create a vaccum, reducing the height of the lay and holding it in place. The carriage supporting the cutting head has two synchronised servo motors which drive it on tracks on the edges of the table. A third servo motor positions the cutting head on a beam across the width of the carriage. These two movements are co ordinated to give a knife position at any point on the table. The cutting head contains a knife automatic sharpener and a further servo motor which rotates the knife to position it at a tangent to the knife with inevitably.

Computerized cutting systems are achieving more widespread use as technology costs decrease and labor costs rise. These computer-driven automated cutters utilize vacuum technology to hold stacks of fabric in place while cutting. Cutting blades are sharpened automatically based upon the type of fabric being cut. Gerber Garment Technology manufactures one of the most commonly used cutting systems. This technology has the advantage of being highly accurate and fast, but does cost considerably more than other cutting techniques.

Advantage
Very active & fast cutting by computer controlledsystem. Suitable for very large-scale production. Speed of cutting can be controlled. Cutting defects are less than other.-Less labor cost.-No need of marker paper.

Disadvantage
Very expensive machine. Higher maintenance cost.

Laser cutting
As a brand new processing method, laser cutting processing depends on its precise processing, faster, simple operation, high degree of automation has been widly used in the leather and textile garment industry. Compared with the traditional cutting method, laser cutting machine not only with low price, low consume, moveover laser processing doesn't have mechanical stress to the workpiece, so the precision and cutting speed of the cutted products' result are very well. Laser cutting machine set of optical, mechanical, electrical as one, with processing of accurate, fast, simple operation, high automation advantages, now in the textile and garment, leather and other industries increasingly wide range of applications, and promote the textile and garment related industries such as fast development. laser cutting machine has a low price, low consumption, the other because the laser processing on the processing of the workpiece without mechanical pressure, so the effect of cutting out the product, precision, and cutting speed are very good. No flash, size standard, the error is small (0.1mm), effect of soft, non-high-frequency or blunt knife cutting sense of pressure, high efficiency, low cost, computer design graphics can be cut out of any shape, any design, any size, lace, etc. , are compared with traditional laser cutting machine cutting machine and hand cut a huge advantage.

Advantage Very high speed cutting Suitable for single ply cuttingDisadvantage:Not suitable for cutting multi layer of fabric Not suitable for synthetic fabric Possibility of burning

Plasma Cutting Machine
Plazma cutting was originally developed to satisfy our demand for high quality cutting. On stainless steel ansd alluminium. But it can also be used to cut textile material ( ionized gas is used )

Water jet cutting
A very high velocity, small diameter stream of water is created by applying high pressure water to a nozzle. The high pressure jet acts as a solid tool when it encounters the material to be cut, tearing the fibres on impact. As the jet penatrates succesive plies in a spread, the momentum decreases and cutting ability is reduced. The jet spread out and cut is wider and rougher at the bottom of the spread. Here the jet of water is normally caught and drained away. There is a danger of wet edges and water spotting. The water used must be filtered de-ionised. Water jet cutting is most effective with harder sheet materials, including leather and plastic. A complete computer system has been developed for leather in which hides are inspected and blemises marked, and the hides are then scanned into the computer. A marker plan is made in which the patterned pieces are planned into the hide, allowing for blemishes and for the varying thicknesses that occur in leader, and the hide is then autamatically cut, in a single layer, by water jet.

Advantage
Very fast cutting operation Not require to sharp the blade

Disadvantage
Capital costs are high Water is to be filtered and de-ionized

Ultrasonic cutting machine
Most recently developed is a cutting system using an ultrasonically driven knife blade . Vibration frequencies in the 20 k hz range produce1/20 mm movement in the blade, small enough to remove the need for a bristle base to the cutting table. Disposable knife blades save sharpening time an dlast for 10-14 days. In the systems developed so far, two cutting heads are used, moving in different but synchronised paths. Up to 10 plies can be cut and low vacuum only is needed.